Adsorption of olefins by petroleum coke



Patented Apr. 21, 1953 ABSORPTION OF OLEFINS BY PETROLEUIVI COKE Francis M. Archibald and William A." Konrad, Elizabeth, and Roy E. D. Haney, Westfield, N. J., assignors to Standard Oil Development Company, a corporation of Delaware 2 No Drawing. Application August 22, 1949,

Serial No. 111,772

This invention relates to the selective adsorption of gaseous olefin hydrocarbons from mixtures thereof with gaseous paraffin hydrocarbons by means of selective adsorption of the olefin when the hydrocarbon mixture containing olefins and paraffins, including normal and iso-para'fiins, is brought into contact with a petroleum coke 'the nature of which is hereinafterexplained.

It is well known that activated carbons possess the property of separating gaseous hydrocarbons according to molecular weight, the selectivity in separatinga binary mixture being for the higher molecular weight component. It has now been discovered that coke recovered from the calcining of petroleum acid sludges displays on the contrary a selective afiinity for olefin, or unsaturated hydrocarbons in preference to the paraifin or saturated hydrocarbons. It has also been found that this selectivity and also the capacity of the coke for the olefin can be enhanced by treating such a coke with nitrogen ata temperature of 1600-1800 F. for a period of 15 minutes to 2 hours, preferably 20 to 60 minutes.

Acid sludges are produced as a result of various petroleum refining operations particularly the sulfuric acid treatment of gasoline, lubricating oils and higher-boiling petroleum distillates particularly phenol extracted oil from which the so-called white oils are prepared by treatment with fuming sulfuric acid or $03. The resulting acid layers from the above treating operations vary in character depending upon the severity of the acid treatment but in general consist of a carbonaceous residue admixed with unreacted sulfuric acid, sulfonic acids, sulfur derivatives and water from which :a tarry residue-called a sludge is obtained upon the settling of the acid layer. e Y

The activated petroleum coke which is employed in this invention is prepared as follows: The tarry sludge is introduced into a decomposition zone. In the decomposition zone the sludge is carbonized by contacting it in the absence of air with a mass of hot coke maintained with continuous stirring at a temperature of 400 F. to about 750 F., preferably about 600 F. to 700.F. for a period of time sufficient to distill therefrom the bulk of the volatile matter present in the sludge. During the carbonization the weight of coke to sludge is maintained at :a ratio from about 2:1 to about 6:1. The carbonized sludge is then transferred to a kiln where it is partially burned with air at a temperature of 650 F. to 1200 F., preferably 1000 F. to 1200 F. for a period of time depending upon the type of coke desiredfgenerally to 25 minutes. The bulk of the resulting hot coke is recycled to the decomposition zone to maintain the mass of coke therein and to supply the necessary heat for the higher molecular weight hydrocarbon.

6 Claims. (01. 183-1142) carbonization, the'balance of the coke is removed as the desired product which is cooled and comminuted to desired size. About seven lbs. of hot coke are recycled to-the decomposition zone for each 1 lb. of coke removed as product which is known as petroleum'coke. It is this product "which has been found, contrary to the prior art teaching on carbon adsorbents, to have'selective affinity for olefin hydrocarbons in preference to paraffin hydrocarbons.

The invention is illustrated by the following data obtained from experiments in which gaseous mixtures of ethylene and propane and of ethylene and ethane were passed over a mass of petroleum coke until equilibrium was established. The coke was desorbed by heating under vacuum or by treating at elevated temperature with an inert gas such as nitrogen, helium, etc. Steam is not to be employed if it is desired to reemploy the coke in the adsorption process because it has been found that the action of steam destroys the selective affinity of the coke for olefins and. reverts it to its normal selectivity for paraffins or However, steam may be employed as the desorbing medium if it is desired to re-use the desorbed coke for other purposes such as the normal gasee I TABLE I Adsorption of gaseoushydrocarbons on petroleum coke Ethylene Ethylene from Profrom Ethpane ane Adsorptive Capacity (millimols/gm.) l. 06 1. 77 Percent O H in Feed Gas 45. 92 51. 52 Percent 02114 in Residual Gas 33.55 49.09 Percent O2H4 in Adsorbate in equilibrium vapor 79. 71 55. 03 Separation Factor, a 5 7. 78 l. 27

(Cone. of less adsorbed comp. in vapor) (Cone. of more adsorbed comp. in vapor) (Cone. of more adsorbed comp. in adsorbate) (Cone. of less adsorbed comp. in adsorbate) 2 Indicates the petroleum coke to be selective for the olefin component.

It has further been found that the action of petroleum coke in adsorbing olefin hydrocarbons is enhanced by treating the coke with nitrogen at a temperature of 1600 F. to 1800 F. for

Adsorption (millimols/gm.) 1.2 Percent Cal-I4 in feed gas -o-c a .la 42;9. Percent C2H4 in residual gas 319 Percent C2H4 in adsorbate sas- 29.0 Separation factor, a. 734

It, appears that the rate of adsorption is, en-

hanced bytne nitrogen-treatment, i. "e. to attain given level :Qf adsorption 1653 time is require with the nitrogen-treatedmateriaLsinee appmximately 8. 16% volatile material; "is liberated from thecoke-during thisitreating operation.

The desorptionpf 'theriatadsotbent with nm'w gen mayralso. serve-amenmamas the" vati'on :step whereby theselectivity and capacity of the coke for olefins are enhanced.

The process is applicable to the, adsorption- -separation of 'thenormally gaseous 'o'lefins, i. e. the C2-C5 olefins, including ethylene, propylene, buteneeand amylenes. 1n;general-theadsorption .is carried out 'at a temperature of GO ZOO" :'pref-e1'ably'75--1 00 Fl and-at a, pressure "of 1:422 atmospheres, preferably =-7 atmospheres. The desorption "is c'arrie'd out at temperaturesin the range "of 300-7011 ;F, Eprefei'ably' -ESQ -BSW FX, and at the same :press'ure as "the adsor'fption ate}: or 'lOWei'.

By "the term petroleum coke as employed aim the appended claims is rmeant ia coke prepared from petroleum acid sludges by 1the tmethod :previously described in this specification.

Having described the invention, whatfisic'laimed as new and what is desired to be secured "by Letters Patent is:

1. A process for the separation of ethylene from a mixture comprising ethylene v and propane which comprises contacting "the mixture "with a-cokeiprepared by calcining 'a sulfuric-acidpetroleum whereby the ethylene "is selectively adsorbed and thereafter recovering ethylene from the petroleum coke.

2. A process for the separation of ethylene from a mixture comprising ethylene and propane which comprises contacting the mixture with a "petroleum Icoke prepared by calcining a sulfuric acid-petroleum which coke has been further activated by treatment with nitrogen at 1600 F. to 1800 F. whereby the ethylene is selectively-adsorbedand thereafter recovering ethylene'from the petroleum coke.

3. An-a'ctivated carbon adaptable for thepreferential adsorption of an olefin from a gaseous 4 V hydrocarbon mixture of an -ole"fln hydrocarbon and'a paraffin hydrocarbonin which the paraflin contains a greater number of carbon atoms than the olefin, prepared by calcining a sulfuric acidepetroleum sludge "to form a coke and thereafter treating the coke with nitrogen at a temperature of 1600 F. to 1800 F.

14.:A process "for 'the separation of an olefin "from'a'gas'eouslhydrocarbon mixture of an olefin -hydrocarbonandaparatfin hydrocarbon in which the paraflin contains a greater number of carbon alt0ms-thanthe olefin which comprises contacting the mixture with a coke prepared by calcining a sulfuric acid-petroleum sludge whereby the olefin is selectively adsorbed, and thereafter recovering the adsorbed olefin from thelcoke.

5, A process, for the separation ...of an olefin from a gaseous hydrocarbon mixture. of an olefin hydrocarbon and apara'ffin hydrocarbon inwhich thepara'fiin contains .a greater number oficarbon 'atomsthan 'the olefin, which comprises contacting the mixture with a coke prepared-by calcining a sulfuric, acid-petroleum sludge and subsequently contacting the. coke with nitrogen at 1600" .F. to 1800 It, whereby the olefin "hydrocarbon is .selectively adsorbed, and thereafter recovering the adsorbed olefinfrom the coke.

6. A process'forthepreparation of an activated carbon adaptable for the preferential adsorption of an olefin from a gaseous 'hydrocarbon mixture of an olefinfhydrocarbon and a parafiin hydrocarbon in which the paraffin contains a .greaternumber of carbon atoms than theolefin which comprises contacting petroleum-suliuric acid sludge coke with nitrogen at atemperature orator to. 15800 FRANCIS M.

LA. 'KONRAD. ROY E. D. HANEY.

References "Cited 'in the'file of this patent UNITED STATES PA'IENTS Number Name Date 1,452132'2 Stewart Apr. '17, "1923 1,865,422 Askenasy' s 'July5, 1932 1,872,080 Harris Aug. 1 6, 1932 2,296,438 Hassler et a1 Sept. 22, 1942 2,384,311 'Kearby Sept. "4, "1945 2,393,214 Andrews Jan. 15,1946 2,470,339 Glaussen et a1. May '17, 194'!) 257-65472 Arncildet a1 J Lily 19, 1949 2,485,352 'Bir'ch'er 0013.18, 1949 2,493,911 Brandt Jan. 10, 1950 "2,519,344 Berg Aug. '22, 1950 2,519,874 'Berg Aug. 22, I950 FOREIGN PATENTS Number Country Date 586,766 GreatIBritai'n s Mar. 31,1947 597;895. Great Britain .-Feb.'5,'1948 

1. A PROCESS FOR THE SEPARATION OF ETHYLENE FROM A MIXTURE COMPRISING ETHYLENE AND PROPANE WHICH COMPRISES CONTACTING THE MIXTURE WITH A COKE PREPARED BY CALCINING A SULFURIC ACIDPETROLEUM WHEREBY THE ETHYLENE IS SELECTIVELY ADSORBED AND THEREAFTER RECOVERING ETHYLENE FROM THE PETROLEUM COKE. 